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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2011 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: TypedQueryCallback.html 820 2014-01-22 16:41:52Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.dellroad.stuff.dao;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import javax.persistence.EntityManager;<a name="line.10"></a>
<span class="sourceLineNo">011</span>import javax.persistence.Query;<a name="line.11"></a>
<span class="sourceLineNo">012</span>import javax.persistence.TypedQuery;<a name="line.12"></a>
<span class="sourceLineNo">013</span><a name="line.13"></a>
<span class="sourceLineNo">014</span>/**<a name="line.14"></a>
<span class="sourceLineNo">015</span> * Helper class for building and executing JPA typed queries.<a name="line.15"></a>
<span class="sourceLineNo">016</span> *<a name="line.16"></a>
<span class="sourceLineNo">017</span> * @param &lt;T&gt; query result type, i.e., what the {@link TypedQuery} returns zero or more of<a name="line.17"></a>
<span class="sourceLineNo">018</span> * @param &lt;R&gt; query Java return type, usually either {@code R} or {@code List&lt;R&gt;}<a name="line.18"></a>
<span class="sourceLineNo">019</span> */<a name="line.19"></a>
<span class="sourceLineNo">020</span>public abstract class TypedQueryCallback&lt;T, R&gt; extends QueryCallback&lt;R&gt; {<a name="line.20"></a>
<span class="sourceLineNo">021</span><a name="line.21"></a>
<span class="sourceLineNo">022</span>    /**<a name="line.22"></a>
<span class="sourceLineNo">023</span>     * Execute the query.<a name="line.23"></a>
<span class="sourceLineNo">024</span>     *<a name="line.24"></a>
<span class="sourceLineNo">025</span>     * &lt;p&gt;<a name="line.25"></a>
<span class="sourceLineNo">026</span>     * The implementation in {@link TypedQueryCallback} delegates to {@link #executeQuery(TypedQuery)}.<a name="line.26"></a>
<span class="sourceLineNo">027</span>     * &lt;/p&gt;<a name="line.27"></a>
<span class="sourceLineNo">028</span>     */<a name="line.28"></a>
<span class="sourceLineNo">029</span>    @SuppressWarnings("unchecked")<a name="line.29"></a>
<span class="sourceLineNo">030</span>    protected final R executeQuery(Query query) {<a name="line.30"></a>
<span class="sourceLineNo">031</span>        return this.executeQuery((TypedQuery&lt;T&gt;)query);<a name="line.31"></a>
<span class="sourceLineNo">032</span>    }<a name="line.32"></a>
<span class="sourceLineNo">033</span><a name="line.33"></a>
<span class="sourceLineNo">034</span>    /**<a name="line.34"></a>
<span class="sourceLineNo">035</span>     * Build the query as a {@link TypedQuery}.<a name="line.35"></a>
<span class="sourceLineNo">036</span>     */<a name="line.36"></a>
<span class="sourceLineNo">037</span>    @Override<a name="line.37"></a>
<span class="sourceLineNo">038</span>    protected abstract TypedQuery&lt;T&gt; buildQuery(EntityManager entityManager);<a name="line.38"></a>
<span class="sourceLineNo">039</span><a name="line.39"></a>
<span class="sourceLineNo">040</span>    /**<a name="line.40"></a>
<span class="sourceLineNo">041</span>     * Execute the query. Typically this is implemented in one of these two ways:<a name="line.41"></a>
<span class="sourceLineNo">042</span>     * &lt;blockquote&gt;&lt;code&gt;<a name="line.42"></a>
<span class="sourceLineNo">043</span>     *   return query.getSingleResult();&lt;br /&gt;<a name="line.43"></a>
<span class="sourceLineNo">044</span>     *   return query.getResultList();<a name="line.44"></a>
<span class="sourceLineNo">045</span>     * &lt;/code&gt;&lt;/blockquote&gt;<a name="line.45"></a>
<span class="sourceLineNo">046</span>     */<a name="line.46"></a>
<span class="sourceLineNo">047</span>    protected abstract R executeQuery(TypedQuery&lt;T&gt; query);<a name="line.47"></a>
<span class="sourceLineNo">048</span>}<a name="line.48"></a>
<span class="sourceLineNo">049</span><a name="line.49"></a>




























































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